Organometallic precursor compounds

ABSTRACT

This invention relates to organometallic precursor compounds represented by the formula (L)M(L′) 2 (NO) wherein M is a Group 6 metal, L is a substituted or unsubstituted anionic ligand and L′ is the same or different and is a π acceptor ligand, a process for producing the organometallic precursor compounds, and a method for producing a film, coating or powder from the organometallic precursor compounds.

RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.11/037,085, filed Jan. 19, 2005, now U.S. Pat. No. 7,244,858.

FIELD OF THE INVENTION

This invention relates to organometallic precursor compounds representedby the formula (L)M(L′)₂(NO) wherein M is a Group 6 metal, L is asubstituted or unsubstituted anionic ligand and L′ is the same ordifferent and is a π acceptor ligand, a process for producing theorganometallic precursor compounds, and a method for producing a film orcoating from the organometallic precursor compounds.

BACKGROUND OF THE INVENTION

Chemical vapor deposition methods are employed to form films of materialon substrates such as wafers or other surfaces during the manufacture orprocessing of semiconductors. In chemical vapor deposition, a chemicalvapor deposition precursor, also known as a chemical vapor depositionchemical compound, is decomposed thermally, chemically, photochemicallyor by plasma activation, to form a thin film having a desiredcomposition. For instance, a vapor phase chemical vapor depositionprecursor can be contacted with a substrate that is heated to atemperature higher than the decomposition temperature of the precursor,to form a metal or metal oxide film on the substrate. Preferably,chemical vapor deposition precursors are volatile, heat decomposable andcapable of producing uniform films under chemical vapor depositionconditions.

The semiconductor industry is currently considering the use of thinfilms of various metals for a variety of applications. Manyorganometallic complexes have been evaluated as potential precursors forthe formation of these thin films. A need exists in the industry fordeveloping new compounds and for exploring their potential as chemicalvapor deposition precursors for film depositions.

Molybdenum materials are being considered for a number of applicationsin the electronics industry for next generation devices, includingelectrode, barrier, and lithography. Similar to the interest in tuning amaterial by creating an alloy of a n-type and p-type metal in differentratios (as exemplified by the work by Misra V. et al. at North CarolinaState (IEDM 2001 20.5.1)), molybdenum can be tuned with nitrogenincorporation and/or deposition orientation to generate a similar effect(with the advantage of a single, less expensive source). The workfunction of molybdenum can thus be adjusted significantly (Fonseca, L.R. C., Fall MRS E4.3, 2003 and Mrovek, M., Fall MRS E4.2, 2003).

Another interest in molybdenum materials is for barrier applications(e.g., Cu). Molybdenum nitrides are candidates for this application(Gordon R. et al., Thin Solid Films 1996 288 116). Molybdenum films alsohave applications in the area of lithography, with potential utility forthe engineering of projection lens systems for photolytical patterningof substrates for extreme ultra-violet lithography (EUVL) at the 45 nmtechnology node (Van den hove, L. IEEE 2002).

The industry movement from physical vapor deposition to chemical vapordeposition and atomic layer deposition processes due to the increaseddemand for higher uniformity and conformality in thin films has lead toa demand for suitable precursors for future semiconductor materials. Formolybdenum, the traditional chemical vapor deposition precursors havebeen Mo(CO)₆ and (Et_(x)C₆H_(6-x))₂Mo (a mixture ofbis(ethylbenzene)molybdenum species). The former suffers from being asolid up to its decomposition point of 150° C., and the latter, althougha liquid, does not have a high vapor pressure (˜0.1 torr at 160° C.) andmay deliver inconsistently due to the various species present.(C₇H₈)Mo(CO)₃ is also available, but is a solid (mp=100° C.), and lackssufficient thermal stability to be a highly desirable candidate.

Building from Mo(CO)₆, replacing three CO's with a cyclopentadienyl (Cp)group seems logical since many Cp systems are known chemical vapordeposition precursors and Cp allows excellent tunability for achievingliquid systems. However, [CpMo(CO)₃]⁻ exists as an anion, and thereforeis not sufficiently volatile (note, the dimer of this system is neutral,but has little volatility due to the increased molecular weight).Changing Cp to a similar neutral six electron donor would seem a logicalprogression, thus yielding the aforementioned (C₇H₈)Mo(CO)₃. Althoughthis compound is neutral with perhaps adequate volatility, the otherissue with these tricarbonyl systems is their instability. The lack ofenough strong π-acids, like CO, render the material very electron rich,and make the complex susceptible to premature decomposition. Twopotential pathways are a ‘ring-slip’ for the cycloheptatriene ligandfrom an η⁶ six electron donor to an η⁴ four electron donor (alleviatingthe electron density on molybdenum) or loss of a hydride from thecycloheptatriene ligand creating an aromatic system and creating a lessdonating environment and a molybdenum cation. Another known molecule,(C₆H₆)Mo(CO)₃, suffers from similar instability issues.

While the unsubstituted cyclopentadienyl compound, i.e., CpMo(CO)₂(NO),and the methyl substituted cyclopentadienyl compound, i.e.,(MeCp)Mo(CO)₂(NO), are known materials (Legzdins, P. et al. Inorg.Synth. 1990, 28, 196 and references therein and Rausch, M. D. et al.Organometallics 1983, 2, 1523 and references therein), there appear tobe no prior teachings or work relating to the use of these compounds asprecursors for chemical vapor deposition or atomic layer deposition.

In developing methods for forming thin films by chemical vapordeposition methods, a need continues to exist for chemical vapordeposition precursors that preferably exhibit dual metal gateapplications, are liquid at room temperature, have relatively high vaporpressure and can form uniform films. Therefore, a need continues toexist for developing new compounds and for exploring their potential aschemical vapor deposition precursors for film depositions. It wouldtherefore be desirable in the art to provide a chemical vapor depositionprecursor having dual metal gate applications, a high vapor pressure andthat can form uniform films.

SUMMARY OF THE INVENTION

This invention pertains to chemical vapor deposition and atomic layerdeposition precursors for next generation devices, specificallymolybdenum-containing precursors that exhibit dual metal gateapplications. Molybdenum (Mo) is a ‘mid-gap’ material (i.e., itpossesses an intermediate work function between n-type (˜4.0 eV) andp-type (˜5.0 eV) species), and depending on how it is deposited canserve as both an n- and p-type electrode, as well as for barrier andlithography applications. The physical location of molybdenum on theperiodic table between n-type materials on the left (e.g., Ti, Zr, Hf,Ta) and p-type on the right (e.g, Ni, Pd, Pt, Ir) helps to demonstrateits flexibility.

As an advantage over the n-type species, molybdenum metal is typicallyeasier to deposit than the early transition metals, which have a higheraffinity for forming oxides, carbides, and nitrides. As an advantageover the p-type species, molybdenum is less expensive than the ‘nobel’metals such as palladium and platinum, and likely easier to etch. Also,using a single metal for both types presents a processing advantage.

This invention relates in general to organometallic precursor compoundsrepresented by the formula (L)M(L′)₂(NO) wherein M is a Group 6 metal, Lis a substituted or unsubstituted anionic ligand and L′ is the same ordifferent and is a π acceptor ligand. More particularly, this inventionrelates to organometallic precursor compounds represented by the formula(L)M(CO)₂(NO) wherein M is a Group 6 metal and L is a substituted orunsubstituted anionic ligand. Typically, M is selected from molybdenum,chromium or tungsten, L is selected from a cyclopentadienide,diketonate, amide, cyclic amide, alkoxide, halide or imide, and L′ isselected from CO and alkenes. A preferred organometallic precursorcompound is represented by the formula (RL)Mo(CO)₂(NO) wherein L is asubstituted cyclopentadienyl ligand and R is an alkyl having from 2 toabout 8 carbon atoms. Typically, R is selected from ethyl, propyl,isopropyl, butyl, tert-butyl and SiMe₃.

This invention also relates to a process for producing an organometallicprecursor compound which comprises reacting a Group 6 metal-carbonyland/or alkene source compound, a hydrocarbon or heteroatom-containingcompound and a nitrosyl source compound under reaction conditionssufficient to produce said organometallic precursor compound. Typically,the hydrocarbon or heteroatom-containing compound comprises a lithiatedcyclopentadienide, diketonate, amide, cyclic amide, alkoxide, halide orimide.

This invention also relates to a method for producing a film, coating orpowder by decomposing an organometallic precursor compound representedby the formula (L)M(L′)₂(NO), preferably an organometallic precursorcompound represented by the formula (L)M(CO)₂(NO), wherein M is a Group6 metal, L is a substituted or unsubstituted anionic ligand and L′ isthe same or different and is a π acceptor ligand, thereby producing thefilm, coating or powder. Typically, the decomposing of saidorganometallic precursor compound is thermal, chemical, photochemical orplasma-activated.

The invention has several advantages. For example, the method of theinvention is useful in generating organometallic compound precursorsthat have varied chemical structures and physical properties. Filmsgenerated from the organometallic compound precursors can be depositedwith a short incubation time, and the films deposited from theorganometallic compound precursors exhibit good smoothness.

A preferred embodiment of this invention is that the organometallicprecursor compounds may be liquid at room temperature. In somesituations, liquids may be preferred over solids from an ease ofsemiconductor process integration perspective.

As can be seen from this invention, the solution to the problemsencountered with the molybdenum-containing precursors of the prior artstems from the addition of a nitrosyl ligand. Although similar tocarbonyl (CO) in structure, nitrosyl (NO) is a notably stronger π-acid(by ˜1 V) when binding in its NO⁺ form. This fact leads to the secondkey advantage. Not only does NO stabilize the precursor, e.g.,CpMo(CO)₂(NO), by removing excess electron density from the metalcenter, but the ligand's cationic nature balances the anioniccyclopentadienyl ligand, rendering the overall molecule neutral. Thiscompound is thermally stable, and is only slightly air sensitive (i.e.,it can be manipulated for short periods in air). Although theunsubstituted cyclopentadienyl system is a solid, the substitutedcyclopentadienyl system is a liquid. Finally, the substitutedcyclopentadienyl system appears to have a higher volatility than thebis(ethylbenzene)molybdenum mixture or Mo(CO)₆.

In comparison with the methyl substituted cyclopentadienyl compound,i.e., (MeCp)Mo(CO)₂(NO), of the prior art, the organometallic precursorcompounds of this invention are typically easier to purify, while theunsubstituted cyclopentadienyl compound, i.e., CpMo(CO)₂(NO), of theprior art forms a solid molybdenum complex. In addition, theorganometallic precursor compounds of this invention may be moreconducive to the deposition of pure metal films versus compounds such asthe molybdenum amides, which have been used for nitrides. Howevernitrides and oxides may still be accessible with these systems with theproper choice of co-reactant (e.g., ammonia, oxygen, respectively).

DETAILED DESCRIPTION OF THE INVENTION

As indicated above, this invention relates to organometallic precursorcompounds represented by the formula (L)M(L′)₂(NO), preferablyorganometallic precursor compounds represented by the formula(L)M(CO)₂(NO), wherein M is a Group 6 metal, L is a substituted orunsubstituted anionic ligand, and L′ is the same or different and is a πacceptor ligand. Typically, M is selected from molybdenum, chromium ortungsten, L is selected from a cyclopentadienide, diketonate, amide,cyclic amide, alkoxide, halide or imide, and L′ is selected from CO andalkenes. A preferred organometallic precursor compound is represented bythe formula (RL)Mo(CO)₂(NO) wherein L is a substituted cyclopentadienylligand and R is an alkyl having from 2 to about 8 carbon atoms.Typically, R is selected from ethyl, propyl, isopropyl, butyl,tert-butyl and SiMe₃.

Illustrative organometallic precursor compounds of this inventioninclude, for example, (EtCp)Mo(CO)₂(NO), (PrCp)Mo(CO)₂(NO),(iPrCp)Mo(CO)₂(NO), (BuCp)Mo(CO)₂(NO), (tBuCp)Mo(CO)₂(NO), and the like,wherein Et is ethyl, Pr is propyl, iPr is isopropyl, Bu is butyl and tBuis tert-butyl.

As also indicated above, this invention also relates to a process forproducing an organometallic precursor compound which comprises reactinga Group 6 metal-carbonyl and/or alkene source compound, e.g., Mo(CO)₆and Mo(CO)₃(C₂H₄)₃, a hydrocarbon or heteroatom-containing compound, anda nitrosyl source compound under reaction conditions sufficient toproduce said organometallic precursor compound. Typically, thehydrocarbon or heteroatom-containing compound comprises a lithiatedcyclopentadienide, diketonate, amide, cyclic amide, alkoxide, halide orimide.

This invention also involves a process for producing an organometalliccompound comprising (i) reacting a hydrocarbon or heteroatom-containingmaterial with a base material in the presence of a solvent and underreaction conditions sufficient to produce a first reaction mixturecomprising a hydrocarbon or heteroatom-containing compound, (ii) addinga metal-carbonyl and/or alkene source compound and a nitrosyl sourcecompound to said first reaction mixture, (iii) reacting said hydrocarbonor heteroatom-containing compound with said metal-carbonyl and/or alkenesource compound and nitrosyl source compound under reaction conditionssufficient to produce a second reaction mixture comprising saidorganometallic compound, and (iv) separating said organometalliccompound from said second reaction mixture. The method is particularlywell-suited for large scale production since it can be conducted usingthe same equipment, some of the same reagents and process parametersthat can easily be adapted to manufacture a wide range of products. Themethod provides for the synthesis of organometallic compounds using aprocess where all manipulations are carried out in a single vessel, andwhich route to the organometallic compounds does not require theisolation of an intermediate complex. This method is more fullydescribed in U.S. patent application Ser. No. 10/678,074, filed Oct. 6,2003, which is incorporated herein by reference.

The organometallic precursor compounds of this invention may also beprepared by conventional methods such as described in Legzdins, P. etal. Inorg. Synth. 1990, 28, 196 and references therein.

The metal-carbonyl and/or alkene source compound, e.g., Mo(CO)₆ andMo(CO)₃(C₂H₄)₃, starting material may be selected from a wide variety ofcompounds known in the art. The invention herein most prefers the Group6 metals such as molybdenum, chromium and tungsten. The CO ligands arepreferred π acceptor ligands. Other suitable π acceptor ligands includealkenes.

The concentration of the Group 6 metal-carbonyl and/or alkene compoundstarting material can vary over a wide range, and need only be thatminimum amount necessary to react with the hydrocarbon orheteroatom-containing compound and the nitrosyl source compound and toprovide the given metal concentration desired to be employed and whichwill furnish the basis for at least the amount of metal necessary forthe organometallic compounds of this invention. In general, depending onthe size of the reaction mixture, metal-carbonyl and/or alkene sourcecompound starting material concentrations in the range of from about 1millimole or less to about 10,000 millimoles or greater, should besufficient for most processes.

The nitrosyl source compound may be selected from a wide variety ofcompounds known in the art. Illustrative nitrosyl source compoundsinclude diazald (i.e., N-methyl-N-nitroso-p-toluenesulfonamide),nitrosonium tetrafluoroborate and nitric oxide.

The concentration of the nitrosyl source compound starting material canvary over a wide range, and need only be that minimum amount necessaryto react with the metal-carbonyl compound starting material and thehydrocarbon or heteroatom-containing compound. In general, depending onthe size of the reaction mixture, nitrosyl source compound startingmaterial concentrations in the range of from about 1 millimole or lessto about 10,000 millimoles or greater, should be sufficient for mostprocesses.

The hydrocarbon or heteroatom-containing starting material may beselected from a wide variety of compounds known in the art. Illustrativehydrocarbon or heteroatom-containing compounds include, for example,amines, alcohols, diketones, cyclopentadienes, imines, hydrocarbons,halogens and the like. Preferred hydrocarbon or heteroatom-containingstarting materials include alkyl substituted cyclopentadienes includingtheir alkali metal salts, for example, LiEtCp.

The concentration of the hydrocarbon or heteroatom-containing startingmaterial can vary over a wide range, and need only be that minimumamount necessary to react with the base starting material. In general,depending on the size of the reaction mixture, hydrocarbon orheteroatom-containing starting material concentrations in the range offrom about 1 millimole or less to about 10,000 millimoles or greater,should be sufficient for most processes.

The base starting material may be selected from a wide variety ofcompounds known in the art. Illustrative bases include any base with apKa greater than about 10, preferably greater than about 20, and morepreferably greater than about 25. The base material is preferablyn-BuLi, t-BuLi, MeLi, NaH, CaH, lithium amides and the like.

The concentration of the base starting material can vary over a widerange, and need only be that minimum amount necessary to react with thehydrocarbon or heteroatom-containing starting material. In general,depending on the size of the first reaction mixture, base startingmaterial concentrations in the range of from about 1 millimole or lessto about 10,000 millimoles or greater, should be sufficient for mostprocesses.

In one embodiment, the hydrocarbon or heteroatom-containing compound maybe generated in situ, for example, lithiated amides, alkoxides,diketonates, cyclopentadienides, imides and the like. Generating thehydrocarbon or heteroatom-containing compound in situ in the reactionvessel immediately prior to reaction with the metal source compound isbeneficial from a purity standpoint by eliminating the need to isolateand handle any reactive solids. It is also less expensive.

With the in situ generated hydrocarbon or heteroatom-containing compoundin place, addition of the metal-carbonyl source compound, e.g., Mo(CO)₆,can be performed through solid addition, or in some cases moreconveniently as a solvent solution or slurry. Although certainmetal-carbonyl source compounds are moisture sensitive and are usedunder an inert atmosphere such as nitrogen, it is generally to a muchlower degree than the hydrocarbon or heteroatom-containing compounds,for example, lithiated amides, alkoxides, diketonates,cyclopentadienides, imides and the like. Furthermore, manymetal-carbonyl source compounds such as Mo(CO)₆ are denser and easier totransfer.

The hydrocarbon or heteroatom-containing compounds prepared from thereaction of the hydrocarbon or heteroatom-containing starting materialand the base starting material may be selected from a wide variety ofcompounds known in the art. Illustrative hydrocarbon orheteroatom-containing compounds include, for example, lithiated amides,alkoxides, diketonates, cyclopentadienides, imides and the like.

The concentration of the hydrocarbon or heteroatom-containing compoundscan vary over a wide range, and need only be that minimum amountnecessary to react with the metal-carbonyl source compounds andnitrosyl-source compounds to give the organometallic compounds of thisinvention. In general, depending on the size of the reaction mixture,hydrocarbon or heteroatom-containing compound concentrations in therange of from about 1 millimole or less to about 10,000 millimoles orgreater, should be sufficient for most processes.

The solvent employed in the method of this invention may be anysaturated and unsaturated hydrocarbons, aromatic hydrocarbons, aromaticheterocycles, alkyl halides, silylated hydrocarbons, ethers, polyethers,thioethers, esters, thioesters, lactones, amides, amines, polyamines,nitriles, silicone oils, other aprotic solvents, or mixtures of one ormore of the above; more preferably, diethylether, pentanes, ordimethoxyethanes; and most preferably hexanes or THF. Any suitablesolvent which does not unduly adversely interfere with the intendedreaction can be employed. Mixtures of one or more different solvents maybe employed if desired. The amount of solvent employed is not criticalto the subject invention and need only be that amount sufficient tosolubilize the reaction components in the reaction mixture. In general,the amount of solvent may range from about 5 percent by weight up toabout 99 percent by weight or more based on the total weight of thereaction mixture starting materials.

Reaction conditions for the reaction of the base starting material withthe hydrocarbon or heteroatom-containing material, such as temperature,pressure and contact time, may also vary greatly and any suitablecombination of such conditions may be employed herein. The reactiontemperature may be the reflux temperature of any of the aforementionedsolvents, and more preferably between about −80° C. to about 150° C.,and most preferably between about 20° C. to about 80° C. Normally thereaction is carried out under ambient pressure and the contact time mayvary from a matter of seconds or minutes to a few hours or greater. Thereactants can be added to the reaction mixture or combined in any order.The stir time employed can range from about 0.1 to about 400 hours,preferably from about 1 to 75 hours, and more preferably from about 4 to16 hours, for all steps.

Reaction conditions for the reaction of the hydrocarbon orheteroatom-containing compound with the metal-carbonyl and/or alkenesource compound and the nitrosyl source compound, such as temperature,pressure and contact time, may also vary greatly and any suitablecombination of such conditions may be employed herein. The reactiontemperature may be the reflux temperature of any of the aforementionedsolvents, and more preferably between about −80° C. to about 150° C.,and most preferably between about 20° C. to about 80° C. Normally thereaction is carried out under ambient pressure and the contact time mayvary from a matter of seconds or minutes to a few hours or greater. Thereactants can be added to the reaction mixture or combined in any order.The stir time employed can range from about 0.1 to about 400 hours,preferably from about 1 to 75 hours, and more preferably from about 4 to16 hours, for all steps. In the embodiment of this invention which iscarried out in a single pot, the hydrocarbon or heteroatom-containingcompound is not separated from the first reaction mixture prior toreacting with the metal-carbonyl and/or alkene source compound. In apreferred embodiment, the metal-carbonyl source compound is added to thefirst reaction mixture at ambient temperature or at a temperaturegreater than ambient temperature.

The organometallic compounds prepared from the reaction of thehydrocarbon or heteroatom-containing compound, the metal-carbonyl and/oralkene source compound and the nitrosyl source compound may be selectedfrom a wide variety of compounds known in the art. For purposes of thisinvention, organometallic compounds include compounds having ametal-carbon atom bond as well as compounds having a metal-heteroatombond. Illustrative organometallic compounds include, for example, Group6 metal-containing amides, alkoxides, diketonates, cyclopentadienides,halides, imides and the like.

For organometallic compounds prepared by the method of this invention,purification can occur through recrystallization, more preferablythrough extraction of reaction residue (e.g., hexane) andchromatography, and most preferably through sublimation anddistillation.

Furthermore, this process is not limited to molybdenum-cyclopentadienebased systems. It can also be extended to other metals as well as otheranionic ligands. Examples of other metals include, but are not limitedto, chromium and tungsten. Other ligands include, but are not limitedto, alkoxides, betadiketonates, imides, nitrates, anionic hydrocarbons,halides, carbonates and the like.

Those skilled in the art will recognize that numerous changes may bemade to the method described in detail herein, without departing inscope or spirit from the present invention as more particularly definedin the claims below.

Examples of techniques that can be employed to characterize theorganometallic compounds formed by the synthetic methods described aboveinclude, but are not limited to, analytical gas chromatography, nuclearmagnetic resonance, thermogravimetric analysis, inductively coupledplasma mass spectrometry, differential scanning calorimetry, vaporpressure and viscosity measurements.

Relative vapor pressures, or relative volatility, of organometalliccompound precursors described above can be measured by thermogravimetricanalysis techniques known in the art. Equilibrium vapor pressures alsocan be measured, for example by evacuating all gases from a sealedvessel, after which vapors of the compounds are introduced to the vesseland the pressure is measured as known in the art.

Many organometallic compound precursors described herein are liquid atroom temperature and are well suited for preparing in-situ powders andcoatings. For instance, a liquid organometallic compound precursor canbe applied to a substrate and then heated to a temperature sufficient todecompose the precursor, thereby forming a metal or metal oxide coatingon the substrate. Applying a liquid precursor to the substrate can be bypainting, spraying, dipping or by other techniques known in the art.Heating can be conducted in an oven, with a heat gun, by electricallyheating the substrate, or by other means, as known in the art. A layeredcoating can be obtained by applying an organometallic compoundprecursor, and heating and decomposing it, thereby forming a firstlayer, followed by at least one other coating with the same or differentprecursors, and heating.

Liquid organometallic compound precursors such as described above alsocan be atomized and sprayed onto a substrate. Atomization and sprayingmeans, such as nozzles, nebulizers and others, that can be employed areknown in the art.

In preferred embodiments of the invention, an organometallic compound,such as described above, is employed in gas phase deposition techniquesfor forming powders, films or coatings. The compound can be employed asa single source precursor or can be used together with one or more otherprecursors, for instance, with vapor generated by heating at least oneother organometallic compound or metal complex. More than oneorganometallic compound precursor, such as described above, also can beemployed in a given process.

Deposition can be conducted in the presence of other gas phasecomponents. In an embodiment of the invention, film deposition isconducted in the presence of at least one non-reactive carrier gas.Examples of non-reactive gases include inert gases, e.g., nitrogen,argon, helium, as well as other gases that do not react with theorganometallic compound precursor under process conditions. In otherembodiments, film deposition is conducted in the presence of at leastone reactive gas. Some of the reactive gases that can be employedinclude but are not limited to hydrazine, oxygen, hydrogen, air,oxygen-enriched air, ozone (O₃), nitrous oxide (N₂O), water vapor,organic vapors, ammonia and others. As known in the art, the presence ofan oxidizing gas, such as, for example, air, oxygen, oxygen-enrichedair, O₃, N₂O or a vapor of an oxidizing organic compound, favors theformation of a metal oxide film.

As indicated above, this invention also relates in part to a process forproducing a film, coating or powder. The process includes the step ofdecomposing at least one organometallic compound precursor, therebyproducing the film, coating or powder, as further described below.

Deposition processes described herein can be conducted to form a film,powder or coating that includes a single metal or a film, powder orcoating that includes a single metal oxide. Mixed films, powders orcoatings also can be deposited, for instance mixed metal oxide films. Amixed metal oxide film can be formed, for example, by employing severalorganometallic precursors, at least one of which being selected from theorganometallic compounds described above.

Gas phase film deposition can be conducted to form film layers of adesired thickness, for example, in the range of from about 1 nm to over1 mm. The precursors described herein are particularly useful forproducing thin films, e.g., films having a thickness in the range offrom about 10 nm to about 100 nm. Films of molybdenum, for instance, canbe considered for fabricating metal electrodes, in particular asn-channel metal electrodes in logic, as capacitor electrodes for DRAMapplications, and as dielectric materials.

The process also is suited for preparing layered films, wherein at leasttwo of the layers differ in phase or composition. Examples of layeredfilm include metal-insulator-semiconductor, and metal-insulator-metal.

In an embodiment, the invention is directed to a process that includesthe step of decomposing vapor of an organometallic compound precursordescribed above, thermally, chemically, photochemically or by plasmaactivation, thereby forming a film on a substrate. For instance, vaporgenerated by the compound is contacted with a substrate having atemperature sufficient to cause the organometallic compound to decomposeand form a film on the substrate.

The organometallic compound precursors can be employed in chemical vapordeposition or, more specifically, in metalorganic chemical vapordeposition processes known in the art. For instance, the organometalliccompound precursors described above can be used in atmospheric, as wellas in low pressure, chemical vapor deposition processes. The compoundscan be employed in hot wall chemical vapor deposition, a method in whichthe entire reaction chamber is heated, as well as in cold or warm walltype chemical vapor deposition, a technique in which only the substrateis being heated.

The organometallic compound precursors described above also can be usedin plasma or photo-assisted chemical vapor deposition processes, inwhich the energy from a plasma or electromagnetic energy, respectively,is used to activate the chemical vapor deposition precursor. Thecompounds also can be employed in ion-beam, electron-beam assistedchemical vapor deposition processes in which, respectively, an ion beamor electron beam is directed to the substrate to supply energy fordecomposing a chemical vapor deposition precursor. Laser-assistedchemical vapor deposition processes, in which laser light is directed tothe substrate to affect photolytic reactions of the chemical vapordeposition precursor, also can be used.

The process of the invention can be conducted in various chemical vapordeposition reactors, such as, for instance, hot or cold-wall reactors,plasma-assisted, beam-assisted or laser-assisted reactors, as known inthe art.

Examples of substrates that can be coated employing the process of theinvention include solid substrates such as metal substrates, e.g., Al,Ni, Ti, Co, Pt, Ta; metal silicides, e.g., TiSi₂, CoSi₂, NiSi₂;semiconductor materials, e.g., Si, SiGe, GaAs, InP, diamond, GaN, SiC;insulators, e.g., SiO₂, Si₃N₄, HfO₂, Ta₂O₅, Al₂O₃, barium strontiumtitanate (BST); barrier materials, e.g., TiN, TaN; or on substrates thatinclude combinations of materials. In addition, films or coatings can beformed on glass, ceramics, plastics, thermoset polymeric materials, andon other coatings or film layers. In preferred embodiments, filmdeposition is on a substrate used in the manufacture or processing ofelectronic components. In other embodiments, a substrate is employed tosupport a low resistivity conductor deposit that is stable in thepresence of an oxidizer at high temperature or an optically transmittingfilm.

The process of the invention can be conducted to deposit a film on asubstrate that has a smooth, flat surface. In an embodiment, the processis conducted to deposit a film on a substrate used in wafermanufacturing or processing. For instance, the process can be conductedto deposit a film on patterned substrates that include features such astrenches, holes or vias. Furthermore, the process of the invention alsocan be integrated with other steps in wafer manufacturing or processing,e.g., masking, etching and others.

Chemical vapor deposition films can be deposited to a desired thickness.For example, films formed can be less than 1 micron thick, preferablyless than 500 nanometer and more preferably less than 200 nanometersthick. Films that are less than 50 nanometer thick, for instance, filmsthat have a thickness between about 1 and about 20 nanometers, also canbe produced.

Organometallic compound precursors described above also can be employedin the process of the invention to form films by atomic layer deposition(ALD) or atomic layer nucleation (ALN) techniques, during which asubstrate is exposed to alternate pulses of precursor, oxidizer andinert gas streams. Sequential layer deposition techniques are described,for example, in U.S. Pat. No. 6,287,965 and in U.S. Pat. No. 6,342,277.The disclosures of both patents are incorporated herein by reference intheir entirety.

For example, in one ALD cycle, a substrate is exposed, in step-wisemanner, to: a) an inert gas; b) inert gas carrying precursor vapor; c)inert gas; and d) oxidizer, alone or together with inert gas. Ingeneral, each step can be as short as the equipment will permit (e.g.milliseconds) and as long as the process requires (e.g. several secondsor minutes). The duration of one cycle can be as short as millisecondsand as long as minutes. The cycle is repeated over a period that canrange from a few minutes to hours. Film produced can be a few nanometersthin or thicker, e.g., 1 millimeter (mm).

The process of the invention also can be conducted using supercriticalfluids. Examples of film deposition methods that use supercritical fluidthat are currently known in the art include chemical fluid deposition;supercritical fluid transport-chemical deposition; supercritical fluidchemical deposition; and supercritical immersion deposition.

Chemical fluid deposition processes, for example, are well suited forproducing high purity films and for covering complex surfaces andfilling of high-aspect-ratio features. Chemical fluid deposition isdescribed, for instance, in U.S. Pat. No. 5,789,027. The use ofsupercritical fluids to form films also is described in U.S. Pat. No.6,541,278 B2. The disclosures of these two patents are incorporatedherein by reference in their entirety.

In an embodiment of the invention, a heated patterned substrate isexposed to one or more organometallic compound precursors, in thepresence of a solvent, such as a near critical or supercritical fluid,e.g., near critical or supercritical CO₂. In the case of CO₂, thesolvent fluid is provided at a pressure above about 1000 psig and atemperature of at least about 30° C.

The precursor is decomposed to form a metal film on the substrate. Thereaction also generates organic material from the precursor. The organicmaterial is solubilized by the solvent fluid and easily removed awayfrom the substrate. Metal oxide films also can be formed, for example byusing an oxidizing gas.

In an example, the deposition process is conducted in a reaction chamberthat houses one or more substrates. The substrates are heated to thedesired temperature by heating the entire chamber, for instance, bymeans of a furnace. Vapor of the organometallic compound can beproduced, for example, by applying a vacuum to the chamber. For lowboiling compounds, the chamber can be hot enough to cause vaporizationof the compound. As the vapor contacts the heated substrate surface, itdecomposes and forms a metal or metal oxide film. As described above anorganometallic compound precursor can be used alone or in combinationwith one or more components, such as, for example, other organometallicprecursors, inert carrier gases or reactive gases.

In a system that can be used in producing films by the process of theinvention, raw materials can be directed to a gas-blending manifold toproduce process gas that is supplied to a deposition reactor, where filmgrowth is conducted. Raw materials include, but are not limited to,carrier gases, reactive gases, purge gases, precursor, etch/clean gases,and others. Precise control of the process gas composition isaccomplished using mass-flow controllers, valves, pressure transducers,and other means, as known in the art. An exhaust manifold can convey gasexiting the deposition reactor, as well as a bypass stream, to a vacuumpump. An abatement system, downstream of the vacuum pump, can be used toremove any hazardous materials from the exhaust gas. The depositionsystem can be equipped with in-situ analysis system, including aresidual gas analyzer, which permits measurement of the process gascomposition. A control and data acquisition system can monitor thevarious process parameters (e.g., temperature, pressure, flow rate,etc.).

The organometallic compound precursors described above can be employedto produce films that include a single metal or a film that includes asingle metal oxide. Mixed films also can be deposited, for instancemixed metal oxide films. Such films are produced, for example, byemploying several organometallic precursors. Metal films also can beformed, for example, by using no carrier gas, vapor or other sources ofoxygen.

Films formed by the methods described herein can be characterized bytechniques known in the art, for instance, by X-ray diffraction, Augerspectroscopy, X-ray photoelectron emission spectroscopy, atomic forcemicroscopy, scanning electron microscopy, and other techniques known inthe art. Resistivity and thermal stability of the films also can bemeasured, by methods known in the art.

Various modifications and variations of this invention will be obviousto a worker skilled in the art and it is to be understood that suchmodifications and variations are to be included within the purview ofthis application and the spirit and scope of the claims.

EXAMPLE 1

In a glovebox, Mo(CO)₆ (31.9 grams, 121 mmol) was placed into athree-neck 500 milliliter round-bottom flask containing a stir bar. Alsoin the glovebox, Li(EtCp) (11.5 grams, 115 mmol) was placed into aone-neck 250 milliliter round-bottom flask. To each flask was added 150milliliters of anhydrous inhibitor-free THF, and each was capped withsepta. The flasks were removed from the box and placed in a fume hood.The flask containing the molybdenum reagent was placed into a heatingmantle above a stir plate and clamped into position. A nitrogen inletand an exhaust line (through an oil bubbler at the top rear of the hood)were placed into the side-neck septum via needles. Under a heavynitrogen purge (i.e., vigorous bubbling in the oil bubbler) thecenter-neck septa was removed and a water condenser was attached. Waterflow was initiated (through a ‘fail-safe’ turn wheel device hooked up tothe variac for the heating mantle to discontinue heating if waterfails), and the inlet and outlet lines were copper wired. The top of thecondenser was fitted with a 24/40 t-joint. After a few minutes, thenitrogen/exhaust lines were removed from the septum and attached (withno needles) to the two t-joint hose barbs (using copper wire). Stirringwas commenced.

The Li(EtCp) solution was transferred to the reaction flask by cannulavia pressure transfer. After addition was complete, the two flask septawere replaced with pennyhead stoppers under a heavy purge. Heating wascommenced, and the mixture was brought to reflux under a slow purge ofnitrogen through the t-joint. Reflux was continued for 43 hours (duringwhich time CO gas will evolve and exhaust through the bubbler). Themixture was then allowed to cool to room temperature. While the mixturewas cooling, in the glovebox was prepared a solution of Diazald (i.e.,N-methyl-N-nitroso-p-toluenesulfonamide) (25.0 grams, 115 mmol) in THF(100 milliliters) within a one-neck 150 milliliter round bottom flask.The flask was capped with a septum and brought into the fume hood. Thecontents of the flask were transferred slowly (45 minutes) to thestirring room temperature reaction mixture by pressure transfer viacannula (note: CO evolution will occur quickly, releasing approximately3 liters of CO). Once the Diazald addition was complete, stirring wascontinued for 1 hour, after which the condenser was removed, and thecontents of the flask were filtered in the fume hood through a mediumporosity frit.

The remaining solids were rinsed with THF (4×25 milliliters). Thefiltrate was placed into a 1 liter round-bottom flask and the solventremoved in vacuo (rotovap with N₂ refill). The remaining liquid wasloaded onto a 500 milliliter frit loaded halfway with silica gel with a2 centimeter layer of sand on top. The plug was eluted with pentane.After an initial 500 milliliter of colorless pentane was recovered, 2liters of orange product solution was collected (note: the pentanesolution ‘filtrate’ was still orange when collection was halted). Thesolvent was removed from the product solution in-vacuo (rotovap with N₂refill) and the remaining liquid was transferred to a 100 milliliterround-bottom flask for distillation (crude yield 28.5 grams, 90%). Theproduct was vacuum distilled on a short path apparatus. An earlysublimate fraction (crystalline pale yellow solid) was recoveredinitially and discarded (after NMR analysis). The desired product wasthen collected in a new receiver flask (pot temperature 120° C., headtemperature 70° C., 0.15 torr line gauge). (EtCp)Mo(CO)₂(NO), 25.8 grams(82%), is a vivid orange liquid. (EtCp)Mo(CO)₂(NO) may be handled forshort periods in air, but is best stored under nitrogen. The compoundwas characterized and proven to be >99% pure by NMR, GC-MS/FID, and TGA.Melting point (−10° C.) was determined by DSC.

1. A method for producing a film, coating or powder by decomposing anorganometallic precursor compound represented by the formula(RL)Mo(CO)₂(NO) wherein L is a substituted cyclopentadienyl ligand and Ris an alkyl having from 2 to about 8 carbon atoms or SiMe₃; therebyproducing the film, coating or powder.
 2. The method of claim 1 whereinR is selected from ethyl, propyl, isopropyl, butyl, and tert-butyl. 3.The method of claim 1 wherein the organometallic precursor compound isselected from (EtCp)Mo(CO)₂(NO), (PrCp)Mo(CO)₂(NO), (iPrCp)Mo(CO)₂(NO),(BuCp)Mo(CO)₂(NO), (tBuCp)Mo(CO)₂(NO), and the like, wherein Et isethyl, Pr is propyl, iPr is isopropyl, Bu is butyl and tBu istert-butyl.
 4. The method of claim 1 wherein the decomposing of saidorganometallic precursor compound is thermal, chemical, photochemical orplasma-activated.
 5. The method of claim 1 wherein said organometallicprecursor compound is vaporized and the vapor is directed into adeposition reactor housing a substrate.
 6. The method of claim 5 whereinsaid substrate is comprised of a material selected from the groupconsisting of a metal, a metal silicide, a semiconductor, an insulatorand a barrier material.
 7. The method of claim 6 wherein said substrateis a patterned wafer.
 8. The method of claim 1 wherein said film,coating or powder is produced by a gas phase deposition.
 9. A method forproducing a film, coating or powder by decomposing an organometallicprecursor compound represented by the formula (RL)M(L′)₂(NO) wherein Mis a Group 6 metal, L is a substituted cyclopentadienyl ligand, L′ isthe same or different and is a π acceptor ligand, and R is an alkylhaving from 2 to about 8 carbon atoms or SiMe₃; thereby producing thefilm, coating or powder.
 10. The method of claim 9 wherein R is selectedfrom ethyl, propyl, isopropyl, butyl, and tert-butyl.
 11. The method ofclaim 9 wherein M is selected from molybdenum, chromium or tungsten. 12.The method of claim 9 wherein the organometallic precursor compound isselected from (EtCp)Mo(CO)₂(NO), (PrCp)Mo(CO)₂(NO), (iPrCp)Mo(CO)₂(NO),(BuCp)Mo(CO)₂(NO), (tBuCp)Mo(CO)₂(NO), and the like, wherein Et isethyl, Pr is propyl, iPr is isopropyl, Bu is butyl and tBu istert-butyl.
 13. The method of claim 9 wherein the decomposing of saidorganometallic precursor compound is thermal, chemical, photochemical orplasma-activated.
 14. The method of claim 9 wherein said organometallicprecursor compound is vaporized and the vapor is directed into adeposition reactor housing a substrate.
 15. The method of claim 14wherein said substrate is comprised of a material selected from thegroup consisting of a metal, a metal silicide, a semiconductor, aninsulator and a barrier material.
 16. The method of claim 15 whereinsaid substrate is a patterned wafer.
 17. The method of claim 9 whereinsaid film, coating or powder is produced by a gas phase deposition. 18.A method for producing a film, coating or powder by decomposing anorganometallic precursor compound represented by the formula(RL)M(CO)₂(NO) wherein M is a Group 6 metal, L is a substitutedcyclopentadienyl ligand and R is an alkyl having from 2 to about 8carbon atoms or SiMe₃; thereby producing the film, coating or powder.19. The method of claim 18 wherein R is selected from ethyl, propyl,isopropyl, butyl, and tert-butyl.
 20. The method of claim 18 wherein Mis selected from molybdenum, chromium or tungsten.
 21. The method ofclaim 18 wherein the organometallic precursor compound is selected from(EtCp)Mo(CO)₂(NO), (PrCp)Mo(CO)₂(NO), (iPrCp)Mo(CO)₂(NO),(BuCp)Mo(CO)₂(NO), (tBuCp)Mo(CO)₂(NO), and the like, wherein Et isethyl, Pr is propyl, iPr is isopropyl, Bu is butyl and tBu istert-butyl.
 22. The method of claim 18 wherein the decomposing of saidorganometallic precursor compound is thermal, chemical, photochemical orplasma-activated.
 23. The method of claim 18 wherein said organometallicprecursor compound is vaporized and the vapor is directed into adeposition reactor housing a substrate.
 24. The method of claim 23wherein said substrate is comprised of a material selected from thegroup consisting of a metal, a metal silicide, a semiconductor, aninsulator and a barrier material.
 25. The method of claim 24 whereinsaid substrate is a patterned wafer.
 26. The method of claim 18 whereinsaid film, coating or powder is produced by a gas phase deposition. 27.A method for producing a film, coating or powder by decomposing anorganometallic precursor compound represented by the formula(L)M(L′)₂(NO) wherein M is a Group 6 metal, L is a substituted orunsubstituted anionic ligand selected from a diketonate, amide, cyclicamide, alkoxide, halide or imide, and L′ is the same or different and isa π acceptor ligand; thereby producing the film, coating or powder. 28.The method of claim 27 wherein the organometallic precursor compound isrepresented by the formula (L)M(CO)₂(NO) wherein M is a Group 6 metaland L is a substituted or unsubstituted anionic ligand selected from adiketonate, amide, cyclic amide, alkoxide, halide or imide.
 29. Themethod of claim 27 wherein M is selected from molybdenum, chromium ortungsten.
 30. The method of claim 27 wherein the decomposing of saidorganometallic precursor compound is thermal, chemical, photochemical orplasma-activated.
 31. The method of claim 27 wherein said organometallicprecursor compound is vaporized and the vapor is directed into adeposition reactor housing a substrate.
 32. The method of claim 31wherein said substrate is comprised of a material selected from thegroup consisting of a metal, a metal silicide, a semiconductor, aninsulator and a barrier material.
 33. The method of claim 32 whereinsaid substrate is a patterned wafer.
 34. The method of claim 27 whereinsaid film, coating or powder is produced by a gas phase deposition. 35.A method for producing a film, coating or powder by decomposing anorganometallic precursor compound represented by the formula(L)Mo(L′)₂(NO) wherein L is a substituted or unsubstituted anionicligand selected from a diketonate, amide, cyclic amide, alkoxide, halideor imide, and L′ is the same or different and is a π acceptor ligand;thereby producing the film, coating or powder.
 36. The method of claim35 wherein the organometallic precursor compound is represented by theformula (L)Mo(CO)₂(NO) wherein L is a substituted or unsubstitutedanionic ligand selected from a diketonate, amide, cyclic amide,alkoxide, halide or imide.
 37. The method of claim 35 wherein thedecomposing of said organometallic precursor compound is thermal,chemical, photochemical or plasma-activated.
 38. The method of claim 35wherein said organometallic precursor compound is vaporized and thevapor is directed into a deposition reactor housing a substrate.
 39. Themethod of claim 38 wherein said substrate is comprised of a materialselected from the group consisting of a metal, a metal silicide, asemiconductor, an insulator and a barrier material.
 40. The method ofclaim 39 wherein said substrate is a patterned wafer.
 41. The method ofclaim 35 wherein said film, coating or powder is produced by a gas phasedeposition.